Establishing a session in a packet-switched wireless communications network

ABSTRACT

A packet-switched wireless communications network includes a mobile station and a radio network controller that are able to establish a radio connection therebetween. Messages are exchanges over one or more traffic channels to establish a packet-switched services session between the mobile station and the radio network controller. The radio connection is not closed until all messages for establishing the packet-switched services session have been exchanged between the mobile station and the radio network controller.

TECHNICAL FIELD

The invention relates generally to establishing a session in apacket-switched wireless communications network.

BACKGROUND

Mobile communications systems are made up of a plurality of cells. Eachcell provides a radio communications center through which a mobilestation establishes a call or other communications session with anothermobile station or a terminal connected to either a circuit-switchednetwork (e.g., public-switched telephone network or PSTN) or apacket-switched data network. Each cell includes a radio base station,with each base station coupled to a switching center that controlsprocessing of calls or other communications sessions between or amongmobile stations or between mobile stations and terminals connected to acircuit-switched or a packet-switched network.

Various wireless protocols exist for defining communications in awireless network. One type of protocol is based on the time-divisionmultiple access (TDMA) technology, such as the TIA/EIA-136 standardprovided by the Telecommunications Industry Association (TIA) or theGlobal System for Mobile (GSM) standard. Another type of protocol forwireless communications is based on the code-division multiple access(CDMA) technology. CDMA is a spread spectrum wireless communicationsprotocol in which transmission is based on the spread spectrummodulation technique to allow many users to have access to the same bandof carriers.

Traditionally, wireless networks have been designed for carryingcircuit-switched voice traffic. However, with the wide availability ofthe Internet and intranets, packet-switched communications (e.g., webbrowsing, electronic mail, instant messaging, electronic gaming, and soforth) have become common. As a result, third generation (3G) and beyondwireless technologies are being developed and implemented to providehigher bandwidth and more efficient packet-switched communications (ofdata as well as voice and other forms of real-time data) over wirelessnetworks.

In the CDMA context, a CDMA 2000 family of standards has been developedthat is capable of supporting both traditional circuit-switched wirelesscommunications protocols have also been developed. On the TDMA side,packet-switched wireless communications protocols have also beendeveloped.

The first phase of CDMA 2000 is referred to as 1xRTT (also referred toas 3G1X or 1X), which is designed to increase voice capacity as well asto support data transmission speeds that are faster than typicallyavailable. In addition, for even higher data rates, a High Rate PacketData (HRPD) wireless technology has been developed. HRPD is defined asTIA/EIA/IS-856, “CDMA 2000, High Rate Packet Data Air InterfaceSpecification,” which is adopted by the TIA. The HRPD technology is alsoreferred to as the 1xEV-DO or 1xEV technology. 1xEV-DO providesrelatively high data transfer rates over the air interface betweenmobile stations and base stations.

To establish 1xEV-DO session over a wireless link, various sessionconfiguration messages are exchanged over a radio connection between themobile station and the radio network controller over traffic channels.However, other types of messages for establishing the 1xEV-DO sessionare exchanged on control channels, such as location update messages andhardware identifier messages. Typically, exchanging messages over acontrol channel usually takes longer than exchanging messages overtraffic channels when establishing a 1xEV-DO session.

The 1xEV-DO session establishment is not complete until the locationupdate messages and hardware identifier messages have been exchanged.However, if the mobile station is located near a boundary between tworadio network controllers, handoff may occur from one radio networkcontroller to another radio network controller. As a result of a handoffprocedure, the radio connection may be closed prior to all messagesneeded for 1xEV-DO session establishment being exchanged. Closing theradio connection prior to complete session establishment results in1xEV-DO session establishment failure, since all messages needed forsession establishment has not yet been exchanged. After handoff, themobile station will have to repeat the procedures for establishing the1xEV-DO session with the new radio network controller. Having to repeatsuch procedures is time-consuming and wastes radio resources of thewireless communications network.

SUMMARY

In general, methods and apparatus are provided to efficiently establisha session in a packet-switched wireless communications network. Forexample, a packet-switched wireless communications network includes amobile station and a radio network controller that are able to establisha radio connection therebetween. Messages are exchanged over one or moretraffic channels to establish a packet-switched services session betweenthe mobile station and the radio network controller. The radioconnection is not closed until all messages for establishing thepacket-switched services session have been exchanged between the mobilestation and the radio network controller.

Other or alternative features will become apparent from the followingdescription, from the drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example packet-switched wireless ormobile communications network that incorporates an embodiment.

FIG. 2 is a message flow diagram that depicts procedures according tosome embodiments for establishing a session between a mobile station anda radio network controller in the packet-switched wirelesscommunications network of FIG. 1.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to providean understanding of the present invention. However, it will beunderstood by those skilled in the art that the present invention may bepracticed without these details and that numerous variations ormodifications from the described embodiments may be possible.

Referring to FIG. 1, a wireless communications network 10 has a coveragearea designated generally as 12. In one embodiment, the wirelesscommunications network 10 includes components that operate according tothe CDMA (code-division multiple access) 2000 protocol. CDMA 2000 isdefined by the CDMA 2000 family of standards (collectively referred toas the IS-2000 Standard, which is developed by the Third GenerationPartnership Project 2 (3GPP2)). In other embodiments, other types ofwireless protocols, such as TDMA (time-division multiple access)protocols, can be used for communications in the wireless communicationsnetwork 10.

Optionally, for circuit-switched communications, the wirelesscommunications network 10 includes a base station controller (BSC) 60.For communicating circuit-switched voice traffic, the BSC 60 is coupledto a mobile switching center (MSC) (not shown), which is responsible forswitching mobile station-originated or mobile station-terminatedtraffic. Effectively, the MSC is the interface for signaling and usertraffic between the wireless network 10 and other public-switchednetworks (such as a public-switched telephone network (PSTN) or otherMSCs).

The BSC 60 can also support packet-switched communications, in whichpacket data is communicated between a mobile station and anotherendpoint, which can be a terminal coupled to a data network 34 oranother mobile station that is capable of communicating packet data.Examples of the data network 34 include private networks (such as localarea networks or wide area networks) and public networks (such as theInternet). In one example, the BSC 60 is part of a 1xRTT wirelessnetwork, which supports packet data services through a packet dataserving node (PDSN) 30. The BSC 60 is coupled to the PDSN 30 through adata network 15.

Packet data services involve packet-switched communications. In someembodiments, packet-switched communications are defined by the InternetProtocol (IP). In packet-switched communications, packets or other unitsof data carry payload (including user data) as well as headerinformation including routing information (in the form of addresses)used for routing the packets or data units over one or more paths of thenetwork to a destination endpoint. One version of IP, referred to asIPv4, is described in Request for Comments (RFC) 791, entitled “InternetProtocol”, dated September 1981; and another version of IP, referred toas IPv6, is described in RFC 2460, entitled “Internet Protocol, Version6 (IPv6) Specification”, dated December 1998. The data network 15 can bean IP network.

In addition to, or in place of, nodes that are part of a 1xRTT wirelesssystem, the wireless communications network 10 also includes a 1xEV-DOor 1xEV wireless system that supports packet data services. One versionof 1xEV-DO is defined in the TIA/EIA/IS-856 standard, entitled “CDMA2000 High Rate Packet Data Air Interface Specification”. The 1xEV-DOwireless communications system includes access networks (AN) (alsoreferred to as “radio network controllers” or “RNCs”) 14 and 40, thatprovide data connectivity between a packet-switched data network (suchas the data network 34) and a mobile station 16 or 43 (also referred toas an “access terminal”).

The radio network controllers 14 or 40 are connected to access points 17and 42, respectively. The access point 17 or 42 is an entity used forradio frequency (RF) communications with mobile stations within a cellor cell sector 18 or 41, respectively. The access network 14 or 40 andaccess point 17 or 42 provide coverage in a cell or cell sector 18 or41, respectively. More generally, reference is made to a “cell segment”,which refers to either a cell or cell sector. Also, “mobile station”generally refers to either a mobile station or an access terminal. Also,the term “radio network controller” or “RNC” refers to a 1xEV-DO RNC, a1xRTT BSC, or any other type of radio network controller or base stationcontroller.

Although one implementation is described in the context of a 1xEV-DOsystem, other types of packet-switched wireless systems can be used inother implementations, such as 1xEV-DV (also referred to as 1xEV-DO Rev.D). More generally, a “1xEV” network or system refers to any of thevarious versions of the protocols associated with CDMA 2000 that havebeen evolved to support higher rate packet data transfer. Embodimentscan also be used in other types of packet-switched wireless networks. A“packet-switched wireless network” or “packet-switched wirelesscommunications network” refers to a wireless or mobile communicationsnetwork that is able to provide packet-switched services (e.g.,electronic mail, web browsing, electronic gaming, voice-over-IP, etc.).A 1xEV-DO wireless network is an example of a packet-switched wirelessnetwork that supports packet-switched services without supportingcircuit-switched services. Such a packet-switched wireless network isalso referred to as a “packet-switched services only wireless network.”An RNC in a packet-switched services only wireless network is referredto as a “packet-switched services only RNC.” On the other hand, a 1xRTTwireless network is an example of a packet-switched wireless networkthat supports both packet-switched and circuit-switched services.

The radio network controller 40 includes a controller 62 (to performvarious tasks) and storage 64 (to store data). The mobile station 43also includes a controller 56 (to perform various tasks) and a storage58 (to store data). The radio network controller 14 and mobile station16 are similarly configured.

The radio network controller 14 or 40 is coupled to the PDSN 30 throughthe data network 15, such as an R-P (Radio Packet) transport network, toenable packet-switched communications with the packet-switched datanetwork 34. An R-P transport network (or interface) supportsestablishment of an R-P session, which is a logical connection betweenthe RNC and the PDSN for a particular PPP (Point-to-Point Protocol)session. PPP is described in RFC 1661, entitled “The Point-to-PointProtocol (PPP),” dated July 1994.

During a communications session, packet data is routed between themobile station 16 or 43 and another endpoint through the radio networkcontroller 14 or 40, R-P transport network 15, and PDSN 30. In additionto the R-P transport network 15 being a packet-switched network (e.g.,an IP network), the link between the AP 17 or 42 and the RNC 14 or 40,respectively, can also be a packet-switched network (e.g., an IPnetwork).

Although only two RNCs and APs and one BSC are depicted in FIG. 1, it isnoted that the wireless communications network 10 includes multipleRNCs, APs, and BSCs.

In accordance with some embodiments, a more efficient mechanism isprovided for establishing a 1xEV-DO session between a mobile station 16or 43 and a respective radio network controller 14 or 40. Establishing a1xEV-DO session refers to exchanging predetermined parameters andsettings between the mobile station and the radio network controllersuch that packet-switched communications can be performed.

To establish a 1xEV-DO session, a radio connection is first establishedbetween the mobile station and radio network controller. The radioconnection is established between a connection layer in the mobilestation and a connection layer in the radio network controller. Theconnection layer for 1xEV-DO is described in greater detail inTIA/EIA/IS-856. A “radio connection” refers to a connection establishedbetween the mobile station and radio network controller over thewireless link in which control and traffic channels are defined to carrymessages and information between the mobile station and radio networkcontroller.

In one embodiment, once a radio connection has been established, themobile station is assigned a forward traffic channel, a reverse trafficchannel, and a reverse power control channel. The reverse trafficchannel is used by the mobile station to communicate messages to theradio network controller, and the forward traffic channel is used by theradio network controller to communicate messages back to the mobilestation. The reverse power control channel is used for controlling thepower of the mobile station. In addition to these channels, a controlchannel is also available for communicating other control messagingbetween the mobile station and the radio network controller.

Among the messages that are exchanged over traffic channels of a radioconnection between the mobile station and radio network controller areconfiguration messages, including a ConfigurationRequest message torequest configuration of one or more parameters, and aConfigurationResponse message to select parameter settings. TheConfigurationRequest and ConfigurationResponse messages are exchangedfor establishing a 1xEV-DO session between the mobile station and theradio network controller.

In accordance with some embodiments, in addition to exchanging theconfiguration messages over the traffic channels between the mobilestation and radio network controller, other messages, such as hardwareidentifier messages and location update messages are also exchanged overthe traffic channels, rather than over control channels asconventionally performed in a 1xEV-DO wireless communications network.The hardware identifier messages contain a HardwareIDRequest message(sent by the radio network controller to query the mobile station forits hardware identifier information) and a HardwareIDResponse message(sent by the mobile station in response to the HardwareIDRequestmessage). The hardware identifier of the mobile station includes theequipment serial number (ESN) of the mobile station, or some otherhardware identifier of the mobile station.

The location update messages include a LocationRequest message (which issent by the radio network controller to the mobile station) to determinethe location of the mobile station, and a LocationResponse message (sentby the mobile station to the radio network controller) to indicate thecurrent location of the mobile station. Note that the locationinformation stored in the mobile station is typically assigned by aradio network controller.

Normally, the configuration messages, hardware identifier messages,location update messages, and other messages, must all be exchangedbefore 1xEV-DO session establishment is successful.

To increase the likelihood of success of 1xEV-DO session establishmentin accordance with some embodiments, the radio connection between themobile station and the radio network controller is not terminated untilall messages needed for the establishment of the 1xEV-DO session havebeen exchanged between the mobile station and the radio networkcontroller. Additionally, instead of exchanging messages such as thehardware identifier messages and location update messages over a controlchannel (as conventionally done), some embodiments exchange the messagesover traffic channels.

The benefit of exchanging, for example, the hardware identifier messagesand the location update messages across traffic channels between themobile station and radio network controller, rather than controlchannel(s) between the mobile station and a radio network controller, isthat faster communication of such messages is possible. Typically, ittakes a longer period of time to exchange messages over a controlchannel for establishing a 1xEV-DO session. For example, in someconventional 1xEV-DO systems, the location update procedure on a controlchannel can take up to 15 seconds to complete. By exchanging messagesfor the location update procedure on a traffic channel instead of thecontrol channel, the location update procedure can be performed in underone second, according to some implementations.

The radio network controller and mobile station each includes logic toprevent termination of a radio connection until all messaging forestablishing the 1xEV-DO session have been exchanged. Thus, even if amobile station is at a boundary between two radio network controllers,the handoff from a source radio network controller to a target radionetwork controller is prevented until the 1xEV-DO session has beenestablished. This reduces the likelihood of 1xEV-DO sessionestablishment failure, and thus reduces the likelihood that messages forestablishing a 1xEV-DO session would have to be repeated due to a priorsession establishment failure.

FIG. 2 shows a call flow that illustrates the procedure in response to amobile station being initialized (e.g., being turned on for the firsttime) in a 1xEV-DO wireless network. The mobile station and RNC perform(at 102) an exchange of UATI (Unicast Access Terminal Identifier)messages, including a UATI-Request message, a UATI-Assignment message,and a UATI-Complete message. In this procedure, the RNC assigns a uniqueUATI to the mobile station. After UATI assignment, a 1xEV-DO sessionestablishment procedure between the mobile station and the RNC isstarted.

To enable such an establishment, a radio connection is first established(at 108) between the mobile station and the radio network controller.When the radio connection is open, traffic channels (forward trafficchannel and reverse traffic channel) and a reverse power control channelare assigned to the mobile station. Communications between the mobilestation and the radio network controller are conducted over the assignedchannels, as well as over a control channel.

Messages that can be exchanged over the traffic channels include aConfigurationRequest message (note that a ConfigurationRequest can beinitiated by either the mobile station or the radio network controller).In FIG. 2, the mobile station first sends a ConfigurationRequest message(at 110) to the radio network controller. In response, the radio networkcontroller sends (at 112) a ConfigurationResponse message to the mobilestation. Additional ConfigurationRequest and ConfigurationResponsemessages can be exchanged between the mobile station and radio networkcontroller. In some cases, the radio network controller is the one thatsends a ConfigurationRequest message to the mobile station, with themobile station responding with a ConfigurationResponse message.

In accordance with some embodiments, the hardware identifier requestmessage (HardwareIDRequest) is sent (at 114) over a traffic channel fromthe radio network controller to the mobile station to request thehardware identifier of the mobile station. In response, the mobilestation sends (at 116) the hardware identifier in a hardware identifierresponse message (HardwareIDResponse), also over a traffic channel, tothe radio network controller.

Another message that can be exchanged over a traffic channel is alocation request message (LocationRequest) sent (at 118) from the radionetwork controller to the mobile station. The mobile station then sends(at 120) a location response message (LocationResponse) to the radionetwork controller, also over the traffic channel.

Note that the messages depicted in FIG. 2 are examples of some of themessages exchanged between the mobile station and the radio networkcontroller to establish a 1xEV-DO session. Other messages can also beexchanged between the mobile station and the radio network controllerover the traffic channels.

At this point, the radio network controller determines (at 121) if allprocedures for establishing a 1xEV-DO session has been completed. Ifnot, the radio network controller does not send a configuration completemessage (ConfigurationComplete) message to the mobile station. Notsending the configuration complete message effectively prevents themobile station from terminating the radio connection between the mobilestation and radio network controller. However, if all procedures havebeen performed to successfully complete establishment of the 1xEV-DOsession, then the radio network controller sends (at 122) aconfiguration complete message (ConfigurationComplete) to the mobilestation.

Once the ConfigurationComplete message is sent by the radio networkcontroller, the radio connection between the radio network controllerand a mobile station can be closed, if desired. Note that in aconventional 1xEV-DO wireless communications network, theConfigurationComplete message is usually sent after the configurationmessages have been exchanged.

Next, the RNC sends (at 123) an A11 Registration Request messagecontaining a MSID (mobile station identifier), such as an IMSI(International Mobile Subscriber Identity), to the PDSN. The A11Registration Request message is sent to establish an R-P session (alsoreferred to as an A10 connection) between the RNC and PDSN. The A11Registration Request message is described in RFC 2002, entitled “IPMobility Support” dated October 1996.

The PDSN validates the A11 Registration Request message and accepts theconnection by returning (at 124) an A11 Registration Reply message withan accept indication to the RNC. Next, a PPP establishment procedure isinitiated (at 126) between the mobile station and the PDSN. PPP providesa standard method for transporting multi-protocol packets overpoint-to-point links. Here, the PPP session is to be established betweenthe mobile stations and a PDSN. Once the PPP session has beenestablished, packet data can be communicated (at 128) between the mobilestation and the PDSN.

The tasks performed by the RNC and mobile stations are provided bysoftware routines or modules in the RNC and mobile stations.Instructions of such software routines or modules are stored on one ormore storage devices in the corresponding systems and loaded forexecution on corresponding processors. The processors includemicroprocessors, microcontrollers, processor modules or subsystems(including one or more microprocessors or microcontrollers), or othercontrol or computing devices. As used here, a “controller” refers tohardware, software, or a combination thereof. A “controller” can referto a single component or to plural components (whether software orhardware).

Data and instructions (of the software) are stored in respective storagedevices, which are implemented as one or more machine-readable storagemedia. The storage media include different forms of memory includingsemiconductor memory devices such as dynamic or static random accessmemories (DRAMs or SRAMs), erasable and programmable read-only memories(EPROMs), electrically erasable and programmable read-only memories(EEPROMs) and flash memories; magnetic disks such as fixed, floppy andremovable disks; other magnetic media including tape; and optical mediasuch as compact disks (CDs) or digital video disks (DVDs).

The instructions of the software are loaded or transported to eachentity in one of many different ways. For example, code segmentsincluding instructions stored on floppy disks, CD or DVD media, a harddisk, or transported through a network interface card, modem, or otherinterface device are loaded into the entity and executed ascorresponding software routines or modules. In the loading or transportprocess, data signals that are embodied in carrier waves (transmittedover telephone lines, network lines, wireless links, cables, and thelike) communicate the code segments, including instructions, to theentity. Such carrier waves are in the form of electrical, optical,acoustical, electromagnetic, or other types of signals.

While some embodiments have been disclosed with respect to a limitednumber of embodiments, those skilled in the art will appreciate numerousmodifications and variations there from. It is intended that theappended claims cover such modifications and variations as fall withinthe true spirit and scope of the invention.

1. An article comprising at least one processor-readable storage mediumcontaining instructions that when executed cause a radio networkcontroller in a packet-switched wireless communications network to:establish a radio connection over a wireless link with a mobile station,wherein one or more traffic channels are assigned to the mobile stationin the radio connection; exchange messages over the one or more trafficchannels in the radio connection to establish a packet-switched servicessession with the mobile station; prevent the radio connection from beingclosed by preventing sending of a configuration complete message fromthe radio network controller to the mobile station until messages forestablishing the packet-switched services session have been exchangedbetween the radio network controller and the mobile station, wherein themessages for establishing the packet-switched services session includeat least one hardware identifier message containing a hardwareidentifier of the mobile station, and at least one location updatemessage to obtain a location update of the mobile station; and prevent ahandoff from being performed until the messages including the at leastone hardware identifier message and the at least one location updatemessage for establishing the packet-switched services session have beenexchanged between the radio network controller and the mobile station.2. The article of claim 1, wherein exchanging the messages over the oneor more traffic channels to establish the packet-switched servicessession comprises exchanging messages over the one or more trafficchannels to establish a 1xEV-DO session.
 3. The article of claim 1,wherein exchanging the messages over the one or more traffic channels toestablish the packet-switched services session comprises exchangingmessages over the one or more traffic channels to establish a 1xEVsession.
 4. The article of claim 3, wherein the at least one hardwareidentifier message comprises a HardwareIDRequest message and aHardwareIDResponse message communicated over the one or more trafficchannels.
 5. The article of claim 4, wherein exchanging the messagesover the one or more traffic channels further comprises communicating aConfigurationRequest message and a ConfigurationResponse message overthe one or more traffic channels.
 6. The article of claim 5, wherein theat least one location update message comprises a LocationRequest and aLocationResponse message communicated over the one or more trafficchannels.
 7. A system for use in a packet-switched wirelesscommunications network, comprising: an interface to establish a radioconnection over a wireless link with a mobile station, wherein one ormore traffic channels are assigned to the mobile station in the radioconnection; and a controller to: exchange messages over the one or moretraffic channels in the radio connection to establish a packet-switchedservices session with the mobile station; prevent the radio connectionfrom being closed by preventing sending of a configuration completemessage from the radio network controller to the mobile station untilall messages for establishing the packet-switched services session havebeen exchanged between the radio network controller and the mobilestation; and prevent a handoff from being performed until all messagesfor establishing the packet-switched services session have beenexchanged between the radio network controller and the mobile station.8. The system of claim 7, wherein the packet-switched services sessioncomprises a 1xEV session.
 9. The system of claim 8, wherein the messagesexchanged over the one or more traffic channels comprise a messagecontaining a hardware identifier of the mobile station, and wherein thesending of the configuration complete message from the radio networkcontroller to the mobile station is prevented until all messagesincluding the message containing the hardware identifier forestablishing the packet-switched services session have been exchangedbetween the mobile station and the radio network controller.
 10. Thesystem of claim 9, wherein the hardware identifier comprises a messagecontaining an equipment serial number of the mobile station.
 11. Thesystem of claim 7, wherein the messages exchanged over the one or moretraffic channels comprise one or more messages to obtain a locationupdate of the mobile station, and wherein the sending of theconfiguration complete message from the radio network controller to themobile station is prevented until all messages including the one or moremessages to obtain the location update of the mobile station forestablishing the packet-switched services session have been exchangedbetween the mobile station and the radio network controller.
 12. Thesystem of claim 11, wherein the messages exchanged over the one or moretraffic channels comprise one or more configuration messages relating tothe mobile station.